Investigations have begun into an incident today involving a Qantas Airways Boeing 747-400 that was forced to make an emergency descent and diversion to Manila after a large section of its fuselage separated, resulting in a rapid decompression.

The Australian Transport Safety Bureau (ATSB) says it is dispatching a team of four investigators to the Philippine capital to assist local authorities with the probe into what it describes as “a serious incident”.

Oneworld alliance member Qantas says the aircraft was operating as flight QF30 from Hong Kong to Melbourne and it was forced to divert to Manila after suffering a loss of cabin pressure this morning. On board were 346 passengers and 19 crew, none of whom were injured.

Qantas says the aircraft suffered “a hole in its fuselage”. Pictures released by the Manila International Airport Authority show a large gash several metres long on the right side of the aircraft just forward of the wing exposing part of the cargo hold.

The ATSB says: “At approximately 29,000ft (8,839m), the crew were forced to conduct an emergency descent after a section of the fuselage separated and resulted in a rapid decompression of the cabin.

The crew descended the aircraft to 10,000ft in accordance with established procedures and diverted the aircraft to Manila where a safe landing was carried out. The aircraft taxied to the terminal unassisted, where the passengers and crew disembarked. There were no reported injuries.”

It adds: “Initial information indicates that a section of the fuselage has separated in the area of the forward cargo compartment.”

A spokeswoman for the Manila International Airport Authority says the aircraft is registered as VH-OJK.

According to Flight’s ACAS database the 747-400 has a serial number of 25067 and was delivered new to Qantas by Boeing in 1991. It is powered by Rolls-Royce RB211-524G engines.